Research Projects

In response to a request from Mobile Source Division staff, Sierra has estimated the cost - effectiveness of several possible revisions to the current vehicle inspection and maintenance (I/M) program. Based on effectiveness estimates generated by the CALIMFAC model, the cost/ effectiveness of the current program with and without a variety of possible changes is summarized in Table 1.

As indicated in the table, annual inspection frequency is the least cost/effective of the program changes evaluated, with an incremental cost/effectiveness of $4.67 per pound of hydrocarbons (HC) plus oxides of nitrogen (NOx) emissions in the year 2000 timeframe. However, this is still competitive with the cost/effectiveness of other programs adopted by ARB and the local air pollution control districts. Given the significant increase in emission reductions, a change to annual inspection frequency may warrant further consideration. Other potential program changes, such as more stringent idle emission standards and loaded mode testing, appear to be capable of improving the cost/effectiveness of the current program to an even greater degree.